Various subsea applications require use of flexible conduits, such as risers, umbilicals, and cables. In many cases, these conduits run between a subsea structure and a surface vessel or platform and enable communication between these bodies. To preserve the integrity of the conduit and its associated structures, the conduit generally needs to be maintained in a relaxed and gently bent configuration. This enables a reasonable range of movement without putting the conduit under significant tension.
Distributed buoyancy modules provide a way to induce these subsea “wave” configurations by imparting uplift to selected portions of the conduit. These modules typically have two main components: a flotation unit and a fastening mechanism for coupling the flotation unit to the conduit. Buoyancy modules are widely used in offshore oil and gas explorations and subsea remotely operated vehicles. When used with subsea drilling risers, these buoyancy modules can reduce the top tension of the drilling rigs.
As modern offshore oil and gas rigs move to progressively deeper waters, the technical requirements for buoyancy modules become more stringent. It is desirable to provide a high degree of hydrostatic pressure resistance for deeper water applications along with a low density to enable a consistent physical dimensions of the modules. Since these properties are often inversely related, achieving both simultaneously can be a significant engineering challenge.